(1) Field of Invention
This invention relates to novel methods for preparing fluorinated organic compounds, and more particularly to methods of producing fluorinated olefins.
(2) Description of Related Art
Hydrofluorocarbons (HFCs), including particular hydrofluoroalkanes such as tetrafluoropropenes (e.g., 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf)) are effective refrigerants, fire extinguishants, heat transfer media, propellants, foaming agents, blowing agents, gaseous dielectrics, sterilant carriers, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, displacement drying agents and power cycle working fluids. Unlike chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), both of which potentially damage the Earth's ozone layer, HFO-1234yf does not contain chlorine and, thus, poses no threat to the ozone layer. Also, HFO-1234yf possesses a relatively low Global Warming Potential (GWP) compared to most CFCs and HCFCs.
Methods of synthesizing certain HFOs are known. For example, preparation of HFO-1234yf from trifluoroacetylacetone and sulfur tetrafluoride has been described. See Banks, et al., Journal of Fluorine Chemistry, Vol. 82, Iss. 2, p. 171-174 (1997). Also, U.S. Pat. No. 5,162,594 (Krespan) discloses a process wherein tetrafluoroethylene is reacted with another fluorinated ethylene in the liquid phase to produce a polyfluoroolefin product. These starting materials can be expensive, difficult to handle, and/or result in low yields. However, CCl2═CClCH2Cl can be used as an inexpensive and readily available starting material for the preparation of CH2═CFCF3 using the following three-step process:
However, such multistep processes are generally more complicated and less economical compared to shorter synthesis routes. Accordingly, there remains a need for a direct route to convert readily available and inexpensive starting materials. Such starting materials for the synthesis of HFO-1234yf have heretofore been unknown.